A new series of 6-amino-pyrido[2,3-d]pyrimidine-2,4-dione derivatives 3a–3s were prepared via a facile and efficient reaction from α-azidochalcones and 6-amiouracils. The reactions were performed under mild conditions to produce the corresponding compounds in good to excellent yields. Obtained derivatives 3a–3s were evaluated for α-glucosidase inhibitory activity and all of them exhibited excellent in vitro yeast α-glucosidase inhibition with IC₅₀ values ranging from 78.0 ± 2.0 to 252.4 ± 1.0 μM. For example, the most active compound 3o was around 10-fold more potent than acarbose, a standard drug (IC₅₀ = 750.0 ± 1.5 μM). Kinetic study of compound 3o revealed that it inhibited α-glucosidase in a competitive mode. Molecular modeling studies of the most active compounds 3o, 3i, 3e and 3m were also performed.